1. Field of the Invention
The present invention relates to an electric energy storage device, more particularly, to a capacitor of which internal electric resistance between electrodes and their terminals is greatly reduced by increasing the contact area between the electrodes and terminals using irregular interfaces.
2. Discussion of Related Art
Supplied electric energy is stored in an electric energy storage device. And, the storage device such as a battery, an electrolyte condenser, a double-layered electric condenser or the like supplies an external load with the stored electric energy for operation. When the stored electric energy is applied by the electric energy storage device to the external load, the amount of the supplied electric energy greatly depends on their own internal resistance.
FIG. 1A shows a bird""s-eye view of stacked electrodes of an electric energy storage device such as a capacitor according to a related art, and FIG. 1B shows a bird""s-eye view of a cylindrical electric energy storage device by rolling the device in FIG. 1A for illustrating the stacked and rolled electrodes.
FIG. 2A shows a bird""s-eye view of stacked electrodes of an electric energy storage device having a plurality of terminals according to a related art, and FIG. 2B shows a bird""s-eye view of a cylindrical electric energy storage device by rolling the device in FIG. 2A for illustrating the stacked and rolled electrodes.
Referring to FIG. 1A, an electrode body 110 includes a film type anode electrode 100, a film type cathode electrode 102, an anode terminal 104 connected to the anode electrode 100, and a cathode terminal 106 connected to the cathode electrode 102. And, the film type anode electrode 100 and the film type cathode electrode 102 are stacked and isolated each other by an insulating film(not shown in the drawing).
The anode and cathode electrodes 100 and 102 are formed with films to store electrons. The insulating layer inserted between the electrodes 100 and 102 isolates the anode electrode 100 from the cathode electrode 102. The anode terminal 104 is connected to the anode electrode 100 by welding or riveting, and the cathode terminal 106 is also connected to the cathode electrode 102 by the same method.
Referring to FIG. 1B, a cylindrical electric energy storage device 110 is attained by rolling up the electrode body 110 having the above structure.
The anode and cathode terminals 104 and 106 attached to the anode and cathode electrodes 100 and 102 protrude out of the electrode body 100 so as to transfer the electric energy to the external load.
Another electric energy storage device having a pair of terminals connected to a plurality of corresponding lead wires according to a related art will be explained by referring to FIG. 2A and FIG. 2B so as to reduce the internal electric resistance generated between terminals and relatively-long electrodes.
Referring to FIG. 2A, an electrode body 208 includes a film type anode electrode 200, a film type cathode electrode 202 stacked on the anode electrode 200, an insulating film(not shown in the drawing) inserted between the anode and cathode electrodes 200 and 202, a first to a third lead wire 204a, 204b, and 204c connected to the anode electrode 200 by welding or riveting with constant intervals apart, and a first to a third cathode lead wire 206a, 206b, and 206c connected to the cathode electrode 202 by welding or riveting with constant intervals apart. Namely, the first to third anode and cathode lead wires 204a, 204b, 204c, 206a, 206b, and 206c are separated from one another with predetermined intervals apart.
A cylindrical electric energy storage device is provided by rolling up the electrode body 208 as shown in FIG. 2B.
Referring to FIG. 2B, the first to third anode lead wires 204a, 204b, and 204c are coupled by welding all in one. Then, the welded first to third anode lead wires are connected to an anode terminal 210 by welding.
The first to third cathode lead wires 206a, 206b, and 206c are coupled by welding all in one. Then, the welded first to third cathode lead wires are connected to a cathode terminal 212 by welding.
Therefore, the first to third anode and cathode lead wires 204a/204b/204c, and 206a/206b/206c are connected to the anode and cathode terminals 210 and 212, respectively.
On the other hand, the first to third anode and cathode lead wires 204a, 204b, 204c, 206a, 206b, and 206c can be connected to the corresponding terminals 210 and 212 respectively by rivet joint as well.
FIG. 3 shows a bird""s-eye view of a regular polygon type electric energy storage devide according to a related art for illustrating terminal connections.
Referring to FIG. 3, a plurality of rectangular film type anode electrodes 300 and cathode electrodes 302 are stacked alternatively, and a plurality of insulating films(not shown in the drawing) are inserted between the anode and cathode films 300 and 302, respectively. A plurality of anode and cathode lead wires 308 and 310 are formed by extending predetermined ends of the anode and cathode electrodes 300 and 302 so as to huddle up in different corners to be coupled with an anode terminal 304 and a cathode terminal, respectively. Namely, the lead wires 308 and 310 to be connected to the corresponding terminals may be built in bodies of the electrodes 300 and 302.
In the above-structures electric energy storage device, the anode and cathode lead wires 308 and 310 of the anode and cathode electrodes 300 and 302 are connected to the anode and cathode terminals 304 and 306 by welding or riveting.
Methods of connecting a plurality of cells in an electric energy storage device by jointing anode and/or cathode terminals according to the related art will be explained as follows by referring to FIG. 4 and FIG. 5.
FIG. 4 shows a schematic view of an electric energy storage device using a multi-cell method according to a related art, and FIG. 5 shows a schematic view of an electric energy storage device using a bipolar method according to a related art.
Referring to FIG. 4, anode and cathode terminals + and xe2x88x92 of a plurality of electrode bodies 400-1, 400-2, 400-3, . . . in an electric energy storage device are connected in series using lead wires 402 or plate type conductors 402.
Referring to FIG. 5, anode electrodes 500 are separated from cathode electrodes 502 by insulating layers 504 so as to connect in series a plurality of stacked electrode bodies in an electric energy storage device.
Unfortunately, the electric energy storage device according to the related art, as shown in FIG. 1a and FIG. 1b, when the anode and cathode electrodes are connected by welding or riveting a singe anode terminal and a single cathode terminal, fails to reduce electric resistance generated between the electrodes and terminals because the resistance is proportional to length and inverse proportional to the contact area.
And, in the electric energy storage device according to the related art, as shown in FIG. 2a, FIG. 2b and FIG. 3, a plurality of lead wires are connected to the anode and cathode electrodes of the electrode body to increase the contact area between the electrode body and the anode and cathode terminals by welding. And, the lead wires are again connected to the anode and cathode terminals by welding or riveting.
Thus, the electric energy storage device according to the related art may somewhat reduce the electric resistance between the electrodes and terminals due to the reduced electrode length of each terminal. Yet, the related art requires more complicated fabrication method, thereby decreasing productivity.
Moreover, the electric energy storage device according to the related art has to connect the terminals to the lead wires one by one or stack the electrode bodies one on one with insulators therebetween, when a plurality of storage cells are connected by the terminal connection of the related art,
Accordingly, the present invention is directed to an electric energy storage device that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
The object of the present invention is to provide an electric energy storage device enabling to reduce the internal electric resistance between electrodes and their terminals by improving the connections between the electrode body comprising anode and cathode electrodes and the anode/cathode terminals.
Another object of the present invention is to provide an electric energy storage device of which serial connections between a plurality of storage cells is achieved with ease.
Additional features and advantages of the invention will be set forth in the description which follows and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention, which is inserted in a housing charged with an electrolyte solution, includes at least one electrode body formed by rolling up an anode electrode, a first insulating film, a cathode electrode and a second insulating film, wherein a first protrusion of the anode electrode protrudes from one end of the electrode body and a second protrusion of the cathode electrode protrudes from the other end of the electrode body and wherein the first insulating film isolates the anode electrode from the cathode electrode except the first and second protrusions, an anode terminal connected to the first protrusion of the anode electrode wherein a first contact-extending part is formed at a bottom of the anode terminal, and a cathode terminal connected to the second protrusion of the cathode electrode wherein a second contact-extending part is formed at a bottom of the cathode terminal. Preferably, the device further includes a metal layer formed on surfaces of the first and second protrusions.
Preferably, a pressure adjusting means as a rubber packing is inserted between the housing and the anode and cathode terminals so as to maintain a predetermined constant pressure between the electrode body and the anode and cathode terminals.
Preferably, inlets for injecting the electrolyte are formed at each center of the anode and cathode terminals and wherein a plurality of grooves crossing each other are formed at the bottom surfaces of the anode and cathode terminals.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.